1. Field of the Invention
The present invention relates to a thin film magnetic head and, more particularly, it relates to a thin film magnetic head employed in a magnetic recording/reproducing apparatus which feeds a magnetic tape in the forward and reverse directions to record and reproduce information in a bi-directional manner.
2. Description of the Prior Art
A magnetic head in a magnetic tape recording/reproducing apparatus (hereinafter referred to as a streamer) which is used for backing up a hard disk must be provided with the capability of reading-after-writing. Therefore, such a magnetic head has a recording/reproducing head comprising both a recording head and a reproducing head. The recording head is positioned before the reproducing head relative to the tape travel direction. The reproducing head is positioned after the recording head for record checking and reproducing the recorded data.
In such a streamer, a reciprocative recording/reproducing method called the serial-serpentine method is usually applied in order to record and reproduce successively, or without interruption, on a plurality of tracks. The method requires the two recording/reproducing heads disposed as stated above. These recording/reproducing heads are placed in an inverted arrangement to each other relative to the magnetic tape traveling direction, so that two of the magnetic heads are alternatively used between forward and reverse traveling of the tape. When the tape has traveled in both directions, the magnetic heads are shifted relative to the tape by a distance corresponding to the track pitch to record/reproduce the next track.
As the capacity of magnetic recording/reproducing apparatus has increased in recent years, an attempt to simultaneously reproduce a plurality of tracks has been made so as to enhance the data transfer rate in such a streamer. For that purpose, a thin film magnetic head which is easily multi-channeled is suitable (see U.S. Pat. No. 4,677,036).
FIG. 9 shows a prior art thin film magnetic head of the serial-serpentine type. The thin film magnetic head includes three head chips 11, 12 and 13. The head chip 12 in the middle is provided with two reproducing head portions 14, 15 which are disposed at a spacing or distance corresponding to the track pitch multiplied by an integer. On the other hand, the adjacent head chips 11, 13 are provided with recording head portions 17, 16, respectively. The recording head portion 16 and the reproducing head portion 14 are mated to one recording/reproducing head portion while the recording head portion 17 and the reproducing head portion 15 are mated to another recording/reproducing head portion. In this way, the head portions 16, 14 carry out the recording/reproducing operations when a tape 18 is moved in the direction of arrow A while the head portions 17, 15 do so when the tape 18 is moved in the direction of arrow B.
FIG. 10 shows another prior art thin film magnetic head. The thin film magnetic head of FIG. 10 includes a head chip 22 in the middle having recording head portions 24, 25 and adjacent head chips 21, 23 having respective reproducing head portions 27, 26. In this second magnetic head, the head portions 24, 26 carry out the recording/reproducing operations when the tape 18 is moved in the B direction while the head portions 25, 27 do so when the tape 18 is moved in the A direction.
Thus, in a conventional thin film magnetic head chip, especially the head chip 12 (22) disposed in the middle, the same type of head portions are formed on one substrate; that is, either the reproducing head portions alone or the recording head portions alone are located on one substrate. Hence, where the head chip 12 (22) is employed in a thin film magnetic head of the serial-serpentine type, the head chips 11, 13 (21, 23) must be provided in parallel relation adjacent to the head chip 12 (22), as described above.
However, when the thin film magnetic head is formed of the three head chips 11 to 13 (21 to 23) disposed in parallel relation to each other, it is very difficult to approximately position the head chips 11 to 13 (21 to 23) relative to each other and to keep each head chip and the magnetic tape 18 in an appropriate relative position, resulting in a likelihood of data loss due to azimuth error or positioned deviation from the recording tracks. Since such losses increase as the track width or the recording wavelength is decreased, more accurate positioning of the thin film magnetic head may be required. In addition, high accuracy is required to move the tape in a stable manner on and in contact with the head chips 11 to 13 to any relative position in an effort to minimize magnetic flux leakage in the space between each head chip and the magnetic tape 18.